Notes are just .md (Markdown) files. Within Obsidian, most people refer to them as “notes.”
Your notes are stored in your vault (a folder) or vaults (you can have multiple vaults). Where the vault is, is where you selected under Create new vault. The files in %appdata% are support files for the application, caches, backups, etc.
As mentioned above, your notes are plaintext .md files (which can be mixed in your vault with images, PDFs, or other files you may have imported into your vault).
